Method and apparatus for bending glass

An apparatus for bending a sheet of material heated to a formable state, the sheet having a central portion and a perimeter, said apparatus comprising:

• a rigid mold, said rigid mold having a molding surface;
• a conformable pressing element configured and arranged to reciprocate between a holding position spaced from said rigid mold and a pressing position for pressing and rolling the heated sheet against said rigid mold, said conformable pressing element comprising a flexible diaphragm and being further configured and arranged to assume a generally convex upper surface for pressing the heated sheet and configured and arranged for rolling the heated sheet against said rigid mold for conforming the heated sheet to said molding surface of said rigid mold;
• and
• a frame supporting said flexible diaphragm, said frame including a chamber below said diaphragm and a substantially incompressible, pressurized fluid in said chamber for expanding and urging said flexible diaphragm to assume said generally convex upper surface, and said chamber including a body of compressible fluid to pressurize said incompressible fluid.

An apparatus for bending a sheet of material heated to a formable state, the sheet having a central portion and a perimeter, said apparatus comprising:

• a rigid mold, said rigid mold having a molding surface;
• and
• a flexible diaphragm constructed and arranged to reciprocate between a holding position spaced from said rigid mold and a pressing position for pressing and rolling the sheet against said rigid mold, said flexible diaphragm further constructed and arranged to assume a generally convexed upper surface for pressing the sheet and for rolling the sheet against the rigid mold for conforming the sheet to said molding surface of said rigid mold;
• and
• a frame having an open end, said frame supporting said flexible diaphragm to extend over said open end, and said flexible diaphragm constructed and arranged to flex in and out of said open end of said frame for pressing and rolling the heated sheet against said rigid mold and covering said open end of said frame, said flexible diaphragm and said frame defining a closed chamber, said closed chamber filled with a substantially incompressible fluid and including an inflatable bag, and said inflatable bag being configured to hold a quantity of compressible gas such that said inflatable bag can be inflated and deflated to increase or decrease the pressure in said incompressible fluid.

A bending apparatus for bending a sheet of material heated to a formable state, said bending apparatus comprising:

• a rigid mold;
• a flexible diaphragm constructed and arranged for pressing the heated sheet against said rigid mold, said flexible diaphragm constructed and arranged to extend to form a convex shape said bending apparatus constructed and arranged for relative movement of said rigid mold and said flexible diaphragm between a holding position in which said flexible diaphragm is spaced from said rigid mold and to an initial pressing position and to a final pressing position, said flexible diaphragm initially pressing on a central portion of the heated sheet when said bending apparatus is at said initial pressing position, said flexible diaphragm further constructed and arranged for rolling the heated sheet from its central portion to its peripheral edges for conforming the heated sheet to the rigid mold when said bending apparatus is at said final pressing position;
• and
• a holder for supporting the heated sheet between said rigid mold and said flexible diaphragm, said holder having a support surface, said flexible diaphragm constructed and arranged for pushing said heated sheet through said support surface onto said rigid mold for rolling the heated sheet onto the rigid mold.

A bending apparatus for bending a sheet of material heated to a formable state, said bending apparatus comprising:

• a rigid mold;
• a flexible diaphragm constructed and arranged for pressing the heated sheet against said rigid mold, said flexible diaphragm constructed and arranged to extend to form a convex shape for initially pressing on central portion of the heated sheet, said flexible diaphragm further constructed and arranged for rolling the heated sheet its central portion to its peripheral edges for conforming the heated sheet to the rigid mold;
• and
• a holder for supporting the heated sheet between said rigid mold and said flexible diaphragm, said holder comprising a hoop frame and a flexible fabric supported by said hoop frame, said hoop frame having a support surface an inner perimeter and an outer perimeter, said outer perimeter defining opposed sides, and said flexible fabric extending between said opposed sides of said hoop frame and providing said support surface inwardly of said inner perimeter for the heated sheet, said flexible diaphragm constructed and arranged for pushing said heated sheet through said support surface onto said rigid mold for rolling the heated sheet onto the rigid mold.

A bending apparatus for bending a sheet of material heated to a formable state, said bending apparatus comprising:

• a rigid mold;
• a flexible diaphragm configured and arranged for pressing the sheet against said rigid mold, said flexible diaphragm configured and arranged to extend to form a convex shape for initially pressing on a central portion of the heated sheet, said flexible diaphragm further configured and arranged for rolling the heated sheet from its central portion to its peripheral edges for conforming the heated sheet to the rigid mold;
• and
• a holder for supporting the heated sheet between said rigid mold and said flexible diaphragm, said holder comprising a hoop frame and a flexible fabric supported by said hoop frame, said flexible fabric providing a support surface for the heated sheet, said hoop frame including an inner perimeter, and said flexible fabric supporting a weight adjacent said inner perimeter of said hoop frame whereby said flexible fabric is tensioned by said weight to form a generally planar, flexible support surface, and said flexible diaphragm being configured and arranged for pushing said heated sheet through said flexible support surface.

A bending apparatus for bending a sheet of material heated to a formable state, said bending apparatus comprising:

• a rigid mold;
• a flexible diaphragm configured and arranged for pressing the heated sheet against said rigid mold, said flexible diaphragm configured and arranged to extend to form a convex shape for initially pressing on a central portion of the heated sheet, said flexible diaphragm further configured and arranged for rolling the heated sheet from its central portion to its peripheral edges for conforming the heated sheet to the rigid mold;
• a frame supporting said flexible diaphragm, said frame including a pressurized system to extend said flexible diaphragm for pressing the heated sheet, said frame including a chamber below said flexible diaphragm, said chamber holding a substantially incompressible pressurized fluid for extending said flexible diaphragm, and said chamber including an inflatable bag to pressurize said incompressible fluid;
• and
• a holder for supporting the heated sheet between said rigid mold and said flexible diaphragm, said holder having a support surface, and said flexible diaphragm being configured and arranged for pushing the heated sheet through said support surface for rolling the heated sheet onto the rigid mold.

A bending apparatus for bending a sheet of material heated to a formable state the sheet having a central portion and a perimeter, said bending apparatus comprising:

• a press frame;
• a rigid mold supported by said press frame, said rigid mold having at least one molding surface;
• a bladder frame having an open end, at least one of said rigid mold and said bladder frame being constructed and arranged to move from a holding position to a pressing position;
• a holder interposed between said bladder frame and said rigid mold, said holder for supporting the sheet of formable material;
• a flexible membrane supported by said bladder frame over said open end and below said press frame, said flexible membrane defining a chamber with said bladder frame, said chamber including an inlet and outlet through which the chamber is pressurized during a press cycle such that when said chamber is pressurized, said flexible membrane is extended from said bladder frame when said one of said bladder frame and said rigid mold is in said holding position and forms a convex top surface for pressing the heated sheet and for rolling the heated sheet against said molding surface of said rigid mold;
• and
• a control system constructed and arranged to increase or decrease the pressure in said chamber and to move one of said rigid mold and said bladder frame toward the other during the press cycle for pressing the sheet of formable material through said holder and against said rigid mold thereby rolling the heated sheet onto said rigid mold.

A bending apparatus for bending a sheet of material heated to a formable state, said bending apparatus comprising:

• a press frame;
• a rigid mold supported by said press frame, said rigid mold having at least one molding surface;
• a bladder frame having an open end;
• a flexible membrane supported by said bladder frame over said open end and below said bladder frame, said flexible membrane defining a chamber with said press frame, said chamber including an inlet and an outlet through which the chamber is pressurized during a press cycle such that when said chamber is pressurized, said flexible membrane is extended from said bladder frame and forms a convex top surface for pressing the heated sheet and for rolling the heated sheet against said molding surface of said rigid mold, and said chamber being filled with a substantially incompressible fluid in pressure contact with said flexible membrane and an inflatable bladder for increasing the pressure of said incompressible fluid against said flexible membrane;
• and
• a control system configured and arranged to increase or decrease the pressure in said chamber and to move one of said rigid mold and said bladder frame toward the other during the press cycle for rolling the heated sheet onto said rigid mold.

A method of bending a sheet of material heated to a formable state, said method of bending comparing the steps of:

• providing a sheet of material heated to a formable state;
• pressurizing flexible membrane to extend to form a convex outer surface;
• moving one of the pressurized membrane and a rigid mold relative to another of the pressurized flexible membrane and the rigid mold from a holding position with the flexible membrane spaced from the rigid mold to an initial pressing position and a final pressing position;
• and
• pressing one of a central portion and a peripheral portion of the heated sheet with the convex outer surface of the flexible membrane against the rigid mold having one of a convex molding surface and a concave molding surface at the initial pressing position and rolling the heated sheet onto the rigid mold when the one of the pressurized flexible membrane and the rigid mold is move to the final pressing position.

A method of bending a sheet of material heated to a formable state, said method of bending comprising the steps of:

• providing a sheet of material heated to a formable state;
• pressurizing a flexible membrane to extend to form a convex outer surface;
• and
• pressing a portion of the heated sheet with the convex outer surface of the flexible membrane against a rigid mold having one of a convex molding surface and a concave molding surface thereby rolling the heated sheet onto the rigid mold, said pressing a portion of the heated sheet includes pressing a perimeter portion of the heated sheet and rolling the flexible membrane onto the heated sheet from the perimeter portion to a central portion of the heated sheet thereby rolling the heated sheet against the rigid mold.

A method of bending a sheet of material heated to a formable state, said method comprising the steps of:

• providing a sheet of material heated to a formable state;
• rolling the heated sheet onto a rigid mold;
• said rolling including pressurizing a flexible membrane and pressing the pressurized flexible membrane against the heated sheet and against the rigid mold during a press cycle;
• and
• forming a stress mark in the heated sheet.

A method of bending a sheet of material heated to a formable state, said method of bending comprising the steps of:

• providing a sheet of material heated to a formable state;
• rolling the heated sheet onto a molding surface of a rigid mold to form a bent sheet of material, said rolling including pressurizing a flexible membrane and pressing the pressurized flexible membrane against the heated sheet and against the molding surface of the rigid mold during a press cycle;
• and
• inserting an insert into the molding surface of the rigid mold to create a thermal discontinuity in the molding surface to form a stress mark in the bent sheet of material, the insert having a coefficient of thermal conductivity within a range of between about 75 and 99.sup.+ percent less than a coefficient of thermal conductivity of the rigid mold.

A method of bending a sheet of glass comprising the steps of:

• providing a sheet of glass heated to a formable statem, the sheet of glass having a central portion and a periphery;
• positioning the heated glass sheet between a rigid male mold and a conformable pressing member;
• holding the heated glass sheet generally planar between and spaced apart from the rigid male mold and the conformable pressing member before bending;
• pressurizing the conformable pressing member to move the conformable pressing member into a convex shape having an apex;
• moving the conformable pressing member toward the heated glass sheet;
• and
• pushing the central portion of heated glass sheet against the rigid male mold with the apex of the conformable pressing member such that as the conformable pressing member pushes the heated glass sheet against the rigid male mold, the conformable pressing member generally conforms to the shape of the male mold and rolls from the central portion of the heated glass sheet outwardly to the periphery of the heated glass sheet.